Radiation hardenable adhesive composition containing dispersed natural rubber fine particles

ABSTRACT

An adhesive composition comprising natural rubber based particles uniformly dispersed in a radiation setting compound is cured by radiation to make a pressure-sensitive adhesive layer on a substrate, thereby: sufficient adhesiveness is obtained; different fillers sufficiently charged; drying time after application is short; both overall application and pattern application are readily performed; application can be performed on different substrates; and sufficient adhesive strength between the substrate and the pressure-sensitive adhesive layer can be realizes. This adhesive composition may be manufactured by: mixing aqueous emulsion  31  containing the natural rubber based particles  30  and the radiation setting compound  32;  elevating a temperature of the mixture while stirring; removing vaporized water in the aqueous emulsion; and replacing the water as the medium wherein the natural rubber based particles are dispersed with the radiation setting compound.

TECHNICAL FIELD

The present invention relates to an adhesive composition which-has bothadvantages of a natural rubber based adhesive and those of a radiationsetting medium as well as to a sheet for carrying information using it.More particularly, it relates to a sheet for carrying information whichhas concealability and confidentiality including folded sheets andlayered sheets comprising a face as a face and carrying informationwhich is layered by folding and cut-folding as well as a sheet forcarrying information including office supplies such as size-extendablefiling sheets and copying paper where the layered faces adhere.

BACKGROUND ART

Conventionally in the sheet carrying information is carried on thelayered face, a pressure-sensitive adhesive layer is set on the layeredface all over, partially or linearly in the pattern touching oppositelyso that the layered sheets adhere each other, usually when layered. Inthis pressure-sensitive adhesive which is also referred to asself-adhering pressure-sensitive adhesive, each polymer adheres closelythrough self-diffusion or anchor effect by strong pressure exerted inthe state where adhesive layers are touched oppositely each other, andperpetual adhesiveness or detachable adhesiveness is embodied dependingon the composition type or degree of pressuring.

As an example of such sheets for carrying information, a postcard systemand the like which have concealability and confidentiality have beenmade practicable becoming popular.

Examples of postcard systems include those where postcards carryingdifferent information such as private business, copied and printedinformation are folded, cut-folded or where separate post cards arelayered.

In these postcard systems, an adhesive layer is bonded by pressuredetachably in different modes of layering to hide concealable andconfidential information before mailed, then the hidden information isred by the recipient's detaching the layered face.

Further, other examples of postcard systems which have concealabilityand confidentiality include the one where an adhesive layer is bonded bypressure undetachably to confidential information before mailed, thenthe hidden information is red by the recipient's tearing off theadhering part and reopening the layered face.

Adhesive composition forms to be applied on the substrate of the sheetfor carrying information such as concealable and confidential postcardsystems described above include solution, aqueous solution, emulsion(latex), nonsolvent and solid. Adhesive compositions in the form ofaqueous solution and emulsion are generally aqueous while those in theform of solution, nonsolvent and solid are generally nonaqueous.

As aqueous pressure-sensitive adhesive compositions, emulsions ofnatural rubber latex are popular which have advantages including thatthey have high adhesive strength, different fillers may be added, theycan be applied also on the high absorption substrate such as highquality paper. However, natural rubber emulsions are not suitable forpattern application where partial area is applied because viscosity ofthe emulsion is low, the applied part of the substrate contracts and soon, though overall application can be exerted easily. In addition,drying after application sometimes requires long time because the mediumis water.

On the other hand, as nonaqueous pressure-sensitive adhesivecompositions, radiation setting medium including acrylic ones arecommonly used, for example, acrylic cured material which is cured byradiation such as an ultraviolet ray, electron ray, X-ray, I-ray andg-ray is used as a pressure-sensitive adhesive as described in JapanesePatent Laid-Open No. 10-265742. For such radiation settingpressure-sensitive adhesive compositions, there are advantages includingthat drying time after application is short, both overall and patternapplication can be easily exerted. However, sometimes lacked adhesivestrength and sufficient filler could not be added as well as they hadsometimes difficulty when applied on high absorption substrate such ashigh quality paper because they were readily absorbed in the substrate.

Further, when two pressure-sensitive adhesive layers obtained fromadhesive compositions described above were bonded by pressure,thereafter, when the pressure-sensitive adhesive layer bonded bypressure was detached, detachment between the substrate and thepressure-sensitive adhesive layer sometimes occurred resulting indamaging the information because adhesive strength between the substrateand the pressure-sensitive adhesive layer was insufficient.

DISCLOSURE OF THE INVENTION

In view of the above situation, the present invention aims to provide anadhesive composition wherein there is sufficient adhesive strengthallowing sufficient filling of different fillers, drying time afterapplication is short, both overall and pattern application can be easilyexerted, application may be exerted on different substrates andsufficient adhesive strength between the substrate and thepressure-sensitive adhesive layer can be realized.

According to the present invention to achieve the above purposes,provided is an adhesive composition, comprising a natural rubber basedparticle uniformly dispersed in a radiation setting compound.

This adhesive composition can be manufactured by a method, comprising:

-   -   mixing an aqueous emulsion containing said natural rubber based        particle with said radiation setting compound; and    -   elevating a temperature of the mixture while stirring, removing        vaporized water from the aqueous emulsion and replacing a water        by said radiation setting compound as a medium wherein the        natural rubber based particle are dispersed.

A pressure-sensitive adhesive layer consisting of a radiation settingmaterial of the above adhesive composition is formed on a substratesheet to manufacture a sheet for carrying information.

For this pressure-sensitive adhesive layer, there is sufficient adhesivestrength allowing sufficient filling of different fillers, drying timeafter application is short, both overall and pattern application can beeasily exerted, application may be exerted on different substrates andsufficient adhesive strength between the substrate and thepressure-sensitive adhesive layer can be realized.

Thus, application of the adhesive composition on the substrate to formthe pressure-sensitive adhesive layer enables manufacturing of the sheetfor carrying information such as secret and confidential informationexcellent in concealability.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic drawing illustrating a preparation method of anadhesive composition.

FIG. 2 is a schematic drawing to illustrate an adhesive layer.

FIG. 3 is a schematic drawing to illustrate a sheet for carryinginformation where an adhesive layer is detectable.

FIG. 4 is a schematic drawing to illustrate a sheet for carryinginformation where an adhesive layer is undetectable.

BEST MODE FOR CARRYING OUT THE INVENTION

By adopting the manufacturing method of the present invention, water asa medium wherein natural rubber based particles are uniformly dispersedmay be displaced with a radiation setting compound without damaginguniform dispersibility. This step is sometimes phase transition.

A radiation setting compound has radiation polymerizable functionalgroups and cured by radiation such as an ultraviolet ray, electron ray,X-ray, i-ray and g-ray. Therefore, the pressure-sensitive adhesive layermay be formed by applying the adhesive composition which contains aradiation setting compound as a nonaqueous adhesive composition on asubstrate followed by curing with radiation such as an ultraviolet ray,electron ray, X-ray, i-ray and g-ray. Further, curing as described inthe present invention is intended to include not only the one owing toformation of the network structure but also include lowering of fluidityfollowing progressing of a polymerization reaction and the like.

The pressure-sensitive adhesive layer contains natural rubber basedparticles to realize uniform and high adhesiveness because naturalrubber based particles are dispersed uniformly in the radiation settingcompound. Further, when curing the radiation setting compound byradiation, it is considered that the radiation setting compound reactswith the natural rubber based particles. Thus, the natural rubber basedparticles may be fixed in the cured material of the radiation settingcompound resulting in achievement of high adhesiveness.

Further, since the adhesive composition has sufficientpressure-sensitive adhesiveness, different fillers may be filledsufficiently as needed in the adhesive composition leading torealization of a wide range of characteristics of the adhesivecomposition.

Furthermore, the medium wherein the natural rubber based particles aredispersed is a nonaqueous radiation setting compound. Therefore, notonly overall application but also pattern application can be donesuccessfully because the adhesive composition has an appropriateviscosity as well as there is little contraction of the applied part ofthe substrate.

In addition, since the medium is a radiation setting compound, dryingafter application may be done quickly.

Further, the medium is a radiation setting compound, besides, itcontains natural rubber based particles, therefore, it is easy tocontrol the rate of the substrate absorbing the adhesive composition.Consequently, application can be done not only on the substrate with lowabsorption but also on the substrate with high absorption such as highquality paper.

Furthermore, when curing the radiation setting compound by a radiation,it is considered that the radiation setting compound absorbed in thesubstrate is cured in the substrate and that the radiation settingcompound also reacts with the substrate. Therefore, adhesive strengthbetween the substrate and the pressure-sensitive adhesive layer can besufficiently realized, and when reading concealed information bydetaching the pressure-sensitive adhesive layer bonded by pressure,detachment between the substrate and the pressure-sensitive adhesivelayer can be controlled to prevent the concealed information from beingdamaged.

The adhesive composition wherein natural rubber based particles, asdescribed above, are uniformly dispersed in the radiation settingcompound is made to contain further a carboxyl group-containing acryliccompound, thereby performance of the pressure-sensitive adhesive layerobtained can be further improved.

In this case of the adhesive composition, the natural rubber basedparticles are uniformly dispersed in a radiation setting mediumcontaining the carboxyl group-containing acrylic compound and theradiation setting compound.

The pressure-sensitive adhesive layer obtained from curing this adhesivecomposition by a radiation contains the natural rubber based particlesand the carboxyl group-containing acrylic compound, thus, uniform andhigh adhesiveness can be realized because the natural rubber basedparticles are uniformly dispersed in the radiation setting medium. Inaddition, when curing the radiation setting medium by a radiation, it isconsidered that the radiation setting compound reacts with the naturalrubber based particles. In this case, it is also considered that thecarboxyl group-containing acrylic compound reacts with the radiationsetting compound and the natural rubber based particles. Thus, thenatural rubber based particles are firmly fixed in the cured material ofthe radiation setting medium, therefore, high adhesiveness may berealized. And the carboxyl group in the carboxyl group-containingacrylic compound is thought to be important for these excellentcharacteristics.

Furthermore, when curing the radiation setting medium containing thecarboxyl group-containing acrylic compound by a radiation, it isconsidered that the radiation setting medium containing the carboxylgroup-containing acrylic compound absorbed in the substrate is cured inthe substrate. It is also considered that the radiation setting mediumcontaining the carboxyl group-containing acrylic compound reacts withthe substrate. Therefore, adhesive strength between the substrate andthe pressure-sensitive adhesive layer can be sufficiently realized, andwhen reading concealed information by detaching the pressure-sensitiveadhesive layer bonded by pressure, detachment between the substrate andthe pressure-sensitive adhesive layer can be controlled to prevent theconcealed information from being damaged.

The present invention will be further described in detail as follows.

Natural Rubber Based Particles

The natural rubber based particles are particles of natural rubber basedrubber and the like being a main ingredient showing adhesive strengththrough pressure-bonding. For the natural rubber type rubber, there isno specific limitation on the natural rubber and others if they have anisoprene skeleton which is a main ingredient of the natural rubber aswell as self adhesiveness similarly to the natural rubber.

However, in order to improve dispersibility and compatibility of thenatural rubber based particles to the radiation setting medium, acopolymer of the natural rubber type rubber with an acrylic monomer ispreferable as the natural rubber based particles.

The acrylic monomer may be (meth)acrylic esters such asmethyl(meth)acrylate, ethyl(meth)acrylate, propyl(meth)acrylate,butyl(meth)acrylate, hexyl(meth)acrylate, octyl(meth)acrylate,2-ethylhexyl(meth)acrylate, decyl(meth)acrylate, dodecyl(meth)acrylate,lauryl(meth)acrylate, lauryl-dodecyl(meth)acrylate,tridecyl(meth)acrylate, cetyl-stearyl(meth)acrylate,stearyl(meth)acrylate, cyclohexyl(meth)acrylate, benzyl(meth)acrylate,and phenyl(meth)acrylate; (meth)acrylic amides such as (meth)acrylicamide and (meth)acrylic methylolamide; reactive acrylic monomers such as(meth)acrylic acid, hydroxyethyl(meth)acrylate,hydroxypropyl(meth)acrylate, hydroxybutyl(meth)acrylate,dimethylaminoethyl(meth)acrylate, diethylaminoethyl (meth)acrylate,butylaminoethyl(meth)acrylate, glycidyl (meth)acrylate, andtetrahydrofurfuryl(meth)acrylate; crosslinking acrylic monomers such asethylene di(meth)acrylate, diethylene glycol di(meth)acrylate,triethylene glycol di(meth)acrylate, tetraethylene glycoldi(meth)acrylate, decaethylene glycol di(meth)acrylate,pentadecaethylene glycol di(meth)acrylate, pentacontahectaethyleneglycol di(meth)acrylate, butylene di(meth)acrylate, allyl(meth)acrylate,trimethylolpropane tri(meth)acrylate, pentaerythritoltetra(meth)acrylate, and diethyleneglycol di(meth)acrylate phthalate,and the like, as well as combinations of two or more of them.

Further, in order to improve fixation of the adhesive composition to thesubstrate, in addition to improve dispersibility of the natural rubberbased particles a copolymer of the natural rubber type rubber with astyrene based monomer is preferable as the natural rubber basedparticles.

The styrene based monomers may be styrene, α-methylstyrene,p-methylstyrene, α-methyl-p-methylstyrene, p-methoxystyrene,o-methoxystyrene, 2,4-dimethylstyrene, chlorostyrene, bromostyrene, andthe like, as well as combinations of two or more of them.

From the above viewpoints, further there is sometimes a case that uses acopolymer of the natural rubber-rubber, the acrylic monomer and thestyrene monomer as the natural rubber based particles. Furthermore, ifnecessary, combinations of two or more of natural rubber based particlesmay be used.

Radiation Setting Compound

For radiation setting compounds, there is no specific limitation if theycan perform good medium-replacement and if they are cured well by aradiation. However, from the viewpoints of the medium-replacementproperty, curability and performance of pressure-sensitive adhesivelayer obtained, a radiation setting acrylic compound and a cyclicether-containing radiation setting compound are preferable, ifnecessary, those combinations also may be used.

As the radiation setting acrylic compound, an oligomer having at leastone or more acryloyl or methacryloyl groups is preferable in view ofrealizing good performance of the adhesive composition andpressure-sensitive adhesive layer. Further, more preferred is anoligomer having at least two or more acryloyl or methacryloyl groups.Furthermore, in addition to these (meth)acryloyl groups, one may use anoligomer having simultaneously a radically reactive unsaturated groups.Such unsaturated groups may include an allyl group, a methallyl groupand the like.

Although the type of oligomers is not specifically limited, theweight-average molecular weight is preferably 30-1,000, and used are anoligoethylene glycol, an epoxy resin oligomer, a polyester resinoligomer, a polyamide resin oligomer, an urethane resin oligomer, anoligovinyl alcohol, a phenol resin oligomer and the like.

Specific examples of the above radiation setting acrylic compoundsinclude oligoethylene glycol di(meth)acrylate; nonyl phenol EO modified(n=4) acrylate; epoxy resin oligomer acrylic ester (for example,bisphenol A diglycidyl ether diacrylate); a reaction product of epoxyresin oligomer, acrylic acid, and methyltetrahydrophthalic anhydride; areaction product of epoxy resin oligomer and 2-hydroxyethyl acrylate; areaction product of epoxy resin oligomer diglycidyl ether anddiallylamine; an open ring copolymer ester of glycidyl diacrylate andphthalic anhydride; an ester of methacrylic dimer and polyol; apolyester obtained from acrylic acid, phthalic anhydride, and propyleneoxide; a reaction product of oligoethylene glycol, maleic anhydride, andglycidyl methacrylate; a reaction product of oligovinyl alcohol andN-methylolacrylamide; a product obtained by esterifying oligovinylalcohol by succinic anhydride followed by addition of glycidylmethacrylate; an oligomer obtained by reacting diallyl ester ofpyromellitic dianhydride with p,p′-diaminodiphenyl; a reaction productof a ethylene-maleic anhydride copolymer and allylamine; a reactionproduct of a methyl vinyl ether-maleic anhydride copolymer and2-hydroxyethyl acrylate; a product obtained by further reacting theformer product with glycidyl methacrylate; an urethane oligomer havingan acryloyl group or a methacryloyl group on the opposite ends, of whicholigooxy alkylene segment or saturated oligoester segment, or both ofthem are linked via an urethane bond; isoprene gum or butadiene gum withacryl-modified ends, and the like. Preferably the radiation settingacrylic compounds are oligoethylene glycol di(meth)acrylate and thelike.

Further, if necessary, a photopolymerizable monomer may be used as aradiation setting acrylic compound. Preferable photopolymerizablemonomers may be (meth)acrylic acid; (meth)acrylic-ester, for example,alkyl, cycloalkyl, halogenated alkyl, alkoxyalkyl, hydroxyalkyl,aminoalkyl, tetrahydrofurfuryl, allyl, glycidyl, benzyl; phenoxyacrylate; phenoxy methacrylate; alkylene glycol; mono- or diacrylate,and methacrylate of polyoxyalkylene glycol; trimethylolpropanetriacrylate and methacrylate; pentaerythrite tetraacrylate andmethacrylate and the like; acrylamide, methacrylamide, or thederivatives, for example, acrylamide and methacrylamide mono-substitutedor di-substituted by an alkyl group or a hydroxyalkyl group; diacetoneacrylamide and methacrylamide; N,N′-alkylenebisacrylamide andmethacrylamide, and the like.

Further, for use in a case in which curing contraction is anobstraction, used are, for example, isobornyl acrylate or methacrylate;norbornyl acrylate or methacrylate; dicyclopentenoxyethyl acrylate ormethacrylate; dicyclopentenoxypropyl acrylate or methacrylate, and thelike; an acrylic ester or a methacrylic ester of diethylene glycoldicyclopentenyl monoether; an acrylic ester or a methacrylic ester ofoligooxyethylene or oligopropylene glycol dicyclopentenyl monoether, andthe like; dicyclopentenyl cinnamate, dicyclopentenoxyethyl cinnamate,dicyclopentenoxyethyl monofumarate or difumarate, and the like; a mono-or diacrylate, or a mono- or dimethacrylate of3,9-bis(1,1-bismethyl-2-oxyethyl)-spiro[5,5]undecane,3,9-bis(1,1-bismethyl-2-oxyethyl)-2,4,8,10-tetraoxaspiro[5,5]undecane,3,9-bis(2-oxyethyl)-spiro[5,5]undecane,3,9-bis(2-oxyethyl)-2,4,8,10-tetraoxaspiro[5,5]undecane, and the like; amono- or diacrylate, or a mono- or dimethacrylate of an addition polymerof ethyleneoxide or propyleneoxide of these spiroglycols; a methyletherof these monoacrylates or methacrylates; 1-azabicyclo[2,2,2]-3-octenylacrylate or methacrylate; bicyclo[2.2.1]-5-heptene-2,3-dicarboxylmonoallyl ester, and the like; dicyclopentadienyl acrylate ormethacrylate; dicyclopentadienyl oxyethyl acrylate or methacrylate;dihydrodicyclopentadienyl acrylate or methacrylate, and the like.

Further, if necessary, multi-functional acrylic compounds may be alsoused as radiation setting acrylic compounds. As the multi-functionalacrylic compounds, may be used a (meth)acrylic ester of acopolymerizable α,β-unsaturated polycarboxylic acid, a dimethacrylicacid alkylene glycol ester of dimethacrylic acid ethylene glycol,dimethacrylic acid 1,3-butylene glycol, dimethacrylic acid 1,4-butyleneglycol, dimethacrylic acid propylene glycol and the like, trimethylolpropane EO addition triacrylate and the like.

Further, if necessary, an acrylic monomer, an acrylic oligomer having2-10 of polymerization degree, these mixtures and the like may be usedtogether. In this case, preferred is an oligomer that can be obtained byvinyl polymerization of an acrylic monomer. Preferable examples of theacrylic monomers include (meth)acrylic esters such asmethyl(meth)acrylate, ethyl(meth)acrylate, propyl(meth)acrylate,butyl(meth)acrylate, hexyl(meth)acrylate, octyl(meth)acrylate,2-ethylhexyl(meth)acrylate, decyl(meth)acrylate, dodecyl(meth)acrylate,lauryl(meth)acrylate, lauryl-tridecyl(meth)acrylate,tridecyl(meth)acrylate, cetyl-stearyl(meth)acrylate,stearyl(meth)acrylate, cyclohexyl(meth)acrylate, benzyl(meth)acrylate,and phenyl methacrylate; (meth)acrylic amides such as (meth)acrylicamide and (meth)acrylic methylolamide; reactive acrylic monomers such as(meth)acrylic acid, hydroxyethyl(meth)acrylate,hydroxypropyl(meth)acrylate, hydroxybutyl(meth)acrylate,dimethylaminoethyl(meth)acrylate, diethylaminoethyl(meth)acrylate,butylaminoethyl(meth)acrylate, glycidyl(meth)acrylate, andtetrahydrofurfuryl(meth)acrylate; crosslinking acrylic monomers such asethylene di(meth)acrylate, diethylene glycol di(meth)acrylate,triethylene glycol di(meth)acrylate, tetraethylene glycoldi(meth)acrylate, tetraethylene glycol di(meth)acrylate, decaethyleneglycol di(meth)acrylate, pentadecaethylene glycol di(meth)acrylate,pentacontahectaethylene glycol di(meth)acrylate, butylenedi(meth)acrylate, allyl(meth)acrylate, trimethylolpropanetri(meth)acrylate, pentaerythritol tetra(meth)acrylate, anddiethyleneglycol di(meth)acrylatephthalate, and the like. Two or more ofthese monomers, if necessary, maybe used together and also a mixture ofoligomers having different polymerization degrees may be used.

Further, like paracumyl phenol EO-reformed (n=1) acrylate, those wherean oligomer component of a radiation setting acrylic compound issubstituted with a monomer component may be also used.

On the other hand, for the cyclic ether-containing radiation settingcompound, in order to realize good performance of the adhesivecomposition and pressure-sensitive adhesive layer as well as of aring-opening property of the cyclic ether structure, although there isno specific limitation on the cyclic ether-containing radiation settingcompound, preferred are the cyclic ether-containing radiation settingcompounds containing one or more cyclic ether structures which contain2-12 carbons and 1-5 oxygen. Further, the number of carbons is morepreferably not more than 6, still more preferably not more than 4, andthe oxygen number is preferably not more than 4, more preferably notmore than 2. The number of the cyclic ether structures is morepreferably 2 or more.

More particularly, the cyclic ether structure is preferably thecrosslinking structure including —O—, and preferably a compound with agroup having an epoxy ring such as a glycidyl group.

Further, in addition to the cyclic ether structure, a compound havingsimultaneously a radically reactive unsaturated group may be also used.Such an unsaturated group can include an acryloyl group, methacryloylgroup, allyl group, methallyl group, and the like.

Further, a group having the above cyclic ether structure and anunsaturated group preferably bond with a monomer component and anoligomer component in order to realize good performance of the adhesivecomposition and pressure-sensitive adhesive layer.

Although the type of oligomer components is not limited, theweight-average molecular weight is preferably 50-1,000, and used are anoligoethylene glycol, epoxy resin oligomer, polyester resin oligomer,polyamide resin oligomer, urethane resin oligomer, oligovinyl alcohol,phenol resin oligomer, and the like.

A compound wherein the cyclic ether structure bonds with these oligomercomponents may include, for example, oligoethylene glycol diglycidylether.

In addition, the type of monomer components is preferably a monomer ofthe oligomer component as described above, and a compound wherein thecyclic ether structure bonds with such a monomer component may include,for example, ethylene glycol diglycidyl ether as an example of twoglycidyl groups while trimethylol propane tridiglycidyl ether as anexample of three glycidyl groups.

Of the radiation setting compounds as described above, the one havingtwo or three radiation polymerizable functional groups in a molecule ispreferable and the one having two radiation polymerizable functionalgroups is more preferable in order to balance between polymerizablilityof the pressure-sensitive adhesive composition and adhesiveness of thepressure-sensitive adhesive layer obtained. Further, if necessary,combinations of two or more of these radiation setting compounds alsomay be used. Furthermore, the radiation polymerizable functional groupis a (meth)acryloyl group and the like when the radiation settingcompound is a radiation setting acrylic compound, and an epoxy groupwhen the radiation setting compound is a cyclic ether-containingradiation setting compound.

In order to realize the adhesive composition obtained and performance ofthe adhesive layer, the ratio of the radiation setting compound to 100parts by weight of the natural rubber based particles is preferably notless than 50 parts by weight, more preferably not less than 80 parts byweight, still more preferably not less than 100 parts by weight, whileit is preferably not more than 500 parts by weight, more preferably notmore than 300 parts by weight, still more preferably 200 parts byweight. Further, if necessary, two or more radiation setting compoundsalso may be used together, and in this case, the total amount ofradiation setting compounds is preferably within the above range.

Depending on the type of the radiation setting compounds used, apolymerization initiator is used together. Polymerization initiators maybe, for example, benzoin, benzoin alkyl ethers such as benzoin ethylether, benzoin-n-propyl ether, benzoin-isopropyl ether, benzoin isobutylether; 2,2-dimethoxy-2-phenylacetophenone, benzophenone, benzyl,diacetyl, diphenylsulfide, eosin, thionin, 9,10-anthraquinone,2-ethyl-9,10-anthraquinone, methyl benzoyl formate, and the like. Thesepolymerization initiators may be used alone or in combination of two ormore of them. The using amount should be 0.1-30 parts by weight to 100parts by weight of the total amount of the radiation setting compound.

Acrylic Compound Containing Carboxyl Group

Although the acrylic compounds containing a carboxyl group are notspecifically limited, in order to sufficiently improve initial adhesivestrength while suppressing temporal increase of adhesiveness of apressure-sensitive adhesive layer having sufficient strength, preferredare, for example, ester form (I) having a structure whereepoxide(meth)acrylate having a hydroxyl group is bonded to apolycarboxylic acid by ester, ester form (II) having a structure where ahydroxy acid or hydroxy acid polymer is bonded to (meth)acrylic acid byester, and (meth)acrylic polymer (III) having a carboxyl group.

The ester form (I) having a structure where the ester ofepoxide(meth)acrylate having a hydroxyl group is bonded to apolycarboxylic acid by ester may be made, for example, as follows.First, performing ring-opening of the epoxide in the presence of(meth)acrylic acid, the ester is synthesized from (meth)acrylic acid andthe epoxide. The ester obtained is thought to be a kind of alcohol whereone hydroxyl group of the 1,2-diol forms an ester bond with(meth)acrylic acid and the other hydroxyl group has an unreactedstructure, also thought to be a kind of β-hydroxy(meth)acrylate. Theseare also referred to as an olefin oxide-modified (meth)acrylic acid andan epoxide(meth)acrylate having a hydroxyl group or simply anepoxide(meth)acrylate.

Next, the epoxide(meth)acrylate obtained is made to react with apolycarboxylic acid to form an ester bond between a hydroxyl group ofthe epoxide(meth)acrylate and a carboxyl group of the polycarboxylicacid. In this case, by making at least one of two or more carboxylgroups of the polycarboxylic acid not react or by separating theunreacted one, the ester form (I) having a carboxyl group is obtained.

Alternatively, after the polycarboxylic acid derivatives such as thepolycarboxylic acid and the anhydride are made to react with an epoxideand obtained is the ester having a hydroxyl group derived from theepoxide and a carboxyl group derived from the polycarboxylic acid, theester (I) having a structure similar to the one as described above maybe obtained by forming an ester bond from this hydroxyl group and thecarboxyl group of (meth)acrylic acid.

In order to sufficiently improve initial adhesive strength whilesuppressing temporal increase of adhesiveness of a pressure-sensitiveadhesive layer having sufficient strength, although the epoxides are notspecifically limited to, preferred are, for example, acyclic olefinoxides such as ethylene oxide, propylene oxide, 1,2-epoxy butane,2,3-epoxy butane, 1,2-epoxy pentane, 2,3-epoxy pentane, 1,2-epoxyhexane, 2,3-epoxy hexane and 3,4-epoxy hexane; cyclic olefin oxides suchas cyclohexene oxide and the like, and of them, preferred are acyclicolefin oxides such as ethylene oxide, propylene oxide and the like.

Further, in order to sufficiently improve initial adhesive strengthwhile suppressing temporal increase of adhesiveness of apressure-sensitive adhesive layer having sufficient strength, althoughpolycarboxylic acids are not also specifically limited, preferred are,for example, saturated aliphatic dicarboxylic acids such as malonicacid, succinic acid, glutaric acid, adipic acid, pimelic acid, subericacid, azelaic acid, sebacic acid, and the like; saturated aliphatictricarboxylic acids such as hexane-2,3,5-tricarboxylic acid and thelike; saturated cyclicaliphatic dicarboxylic acids such ashexahydrophthalic acid, hexahydroisophthalic acid, hexahydroterephthalicacid, and the like; saturated cyclic aliphatic tricarboxylic acids suchas cyclohexane tricarboxylic acid and the like; unsaturated aliphaticdicarboxylic acids such as maleic acid, fumaric acid, and the like;unsaturated cyclic aliphatic dicarboxylic acids such as tetrahydrophthalic acid, tetrahydroisophthalic acid, tetrahydroterephthalic acid,and the like; aromatic dicarboxylic acids such as phthalic acid,isophthalic acid, terephthalic acid, naphthoic dicarboxylic acid and thelike; aromatic tricarboxylic acids such as trimesic acid, trimelliticacid, naphthoic tricarboxylic acid, and the like.

Of them, preferred are saturated aliphatic dicarboxylic acids such asmalonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid,and the like; saturated cyclic aliphatic dicarboxylic acids such ashexahydrophthalic acid, hexahydroisophthalic acid, hexahydroterephthalicacid, and the like; aromatic dicarboxylic acids such as phthalic acid,isophthalic acid, terephthalic acid, naphthoic dicarboxylic acid and thelike, and specifically preferred are saturated aliphatic dicarboxylicacids such as succinic acid and the like; saturated cyclic aliphaticdicarboxylic acids such as hexahydrophthalic acid and the like; andaromatic dicarboxylic acid such as phthalic acid.

As the ester (I) having the above structure, the following generalformula (I) may be illustrated.

wherein R¹ is hydrogen or a methyl group; R² is alkylene which maycontain a cyclic structure of 2-10 carbons; and R³ is alkylene which maycontain a cyclic structure of 1-20 carbons, alkenylene which may containa cyclic structure of 1-20 carbons or arylene of 1-20 carbons.

Further, R² is derived from the above epoxides, preferably derived fromthe above preferable epoxides such as ethylene, propylene, and the like.R³ is derived from the above polycarboxylic acids, preferably derivedfrom the above preferable polycarboxylic acids such as ethylene,1,2-cyclohexylene, o-phenylene and the like.

The ester form (II) having a structure where a hydroxy acid or hydroxyacid polymer is bonded with (meth)acrylic acid by ester may be made by,for example, ester formation through reaction of the hydroxy acid with(meth)acrylic acid, ester formation through reaction of lactone with(meth)acrylic acid, ester formation through reaction of a hydroxy acidpolymer such as oligoester, polyester and the like with (meth)acrylicacid, oligoester and polyester formations through polycondensation of ahydroxy acid in the presence of (meth)acrylic acid, ester formationthrough reaction of oligoester and polyester obtained from ring-openingpolymerization of lactone with (meth)acrylic acid, ring-openingpolymerization of lactone in the presence of (meth)acrylic acid and thelike.

The oligoester and polyester consisting of the hydroxy acid polymer areobtained from polycondensation of a hydroxy acid, and the polymerizationdegree of the hydroxy acid can be made to be the desired value bysetting the reaction ratio as a prescribed value. And by forming anester bond between a hydroxyl group of the hydroxy acid polymer obtainedand a carboxyl group of (meth)acrylic acid, the ester form (II) isobtained.

When polycondensing a hydroxy acid in the presence of (meth)acrylicacid, the (meth)acrylic acid acts as a polymerization-stopping agent,and obtained is the ester form (II) wherein the (meth)acrylic acid isbonded by ester at the terminal of hydroxy groups of oligoester andpolyester obtained by polycondensation of the hydroxy acid. In thiscase, the polymerization degree of the hydroxy acid may be made to bethe desired value by setting the preparation ratio of the (meth)acrylicacid to the hydroxy acid as a prescribed value. For example, asincreased the amount of the (meth)acrylic acid to that of the hydroxyacid, the polymerization degree of the hydroxy acid is reduced, while asreduced the amount of the (meth)acrylic acid to that of the hydroxyacid, the polymerization degree of the hydroxy acid may be increased.

Further, the oligoester and polyester consisting of the hydroxy acidpolymer are obtained from ring-opening polymerization of lactone, andthe polymerization degree of the hydroxy acid can be made to be thedesired value by setting the reaction ratio as a prescribed value. Andby forming an ester bond between a hydroxyl group of the lactone polymerobtained and a carboxyl group of (meth)acrylic acid, the ester form (II)is obtained.

Further, when polymerizing with ring-opening of lactone in the presenceof (meth)acrylic acid, the (meth)acrylic acid acts as apolymerization-stopping agent, and obtained is the ester form (II)wherein the (meth)acrylic acid is bonded by ester at the terminal ofhydroxy groups of oligoester and polyester obtained by ring-openingpolymerization of the lactone. In this case, the polymerization degreeof the lactone can be made to be the desired value by setting thepreparation ratio of the (meth)acrylic acid to the lactone as aprescribed value. For example, as increased the amount of the(meth)acrylic acid to that of the lactone, the polymerization degree ofthe lactone is reduced, while as reduced the amount of the (meth)acrylicacid to that of the lactone, the polymerization degree of the lactonemay be increased.

In order to sufficiently improve initial adhesive strength whilesuppressing temporal increase of adhesiveness of a pressure-sensitiveadhesive layer having sufficient strength, the polymerization degree ofthe hydroxy acid and lactone is not less than 1 as the number-averagepolymerization degree, more preferably not less than 1.1, still morepreferably not less than 1.2, while it is preferably not more than 5,more preferably not more than 4, still more preferably not more than 3.

Although hydroxy acids are not specifically limited, in order tosufficiently improve initial adhesive strength while suppressingtemporal increase of adhesiveness of a pressure-sensitive adhesive layerhaving sufficient strength, preferred are, for example, a saturatedaliphatic hydroxy acid such as glycolic acid, hydroxypropanoic acid,hydroxybutanoic acid, hydroxypentanoic acid, hydroxyhexanoic acid,hydroxyheptanoic acid, hydroxyoctanoic acid, hydroxynonanoic acid,hydroxydecanoic acid, hydroxydodecanoic acid, hydroxytetradecanoic acid,hydroxyoctadecanoic acid; a saturated cyclic aliphatic hydroxy acid suchas hydroxycyclohexanecarboxylic acid; an aromatic hydroxy acid such ashydroxybenzoic acid, hydroxyphenylacetic acid, (hydroxyphenyl)propionicacid, hydroxytoluic acid, hydroxynaphthoic acid, and the like.

Of them, preferred are saturated aliphatic hydroxy acids such ashydroxypropanoic acid; saturated cyclic aliphatic hydroxy acids such ashydroxycyclohexane carboxylic acid; and aromatic hydroxy acids such ashydroxybenzoic acid.

Moreover, although lactones are not also specifically limited, in orderto sufficiently improve initial adhesive strength while suppressingtemporal increase of adhesiveness of a pressure-sensitive adhesive layerhaving sufficient strength, preferred are, for example, α-lactone,β-lactone, γ-lactone such as γ-caprolactone, δ-lactone such asδ-caprolactone, ε-lactone such as ε-caprolactone. Preferably the lactoneis ε-caprolacton.

As ester form (II) having a structure as described above, the followinggeneral formula (II) may be illustrated.

wherein n is an integer or a real number of 1-5; R⁴ is hydrogen or amethyl group; R⁵ is alkylene which may contain a cyclic structure of1-20 carbons, alkenylene which may contain a cyclic structure of 1-20carbons or arylene of 1-20 carbons.

Specifically when there is distribution of a polymerization degree of arepeat structure unit containing, R⁵, n is intended to represent thenumber-average polymerization degree which is not always an integer.When n is 1, the ester form (II) is an ester form of a hydroxy acid with(meth)acrylic acid or an ester form of lactone with (meth)acrylic acid,while when n is greater than 1, it is an ester form of a hydroxy acidpolymer such as oligoester, polyester and the like with (meth)acrylicacid or an ester form of a lactone polymer such as oligoester, polyesterand the like with (meth)acrylic acid. When it is the ester form of thehydroxy acid polymer or the lactone polymer with (meth)acrylic acid, inorder to sufficiently improve initial adhesive strength whilesuppressing temporal increase of adhesiveness of a pressure-sensitiveadhesive layer having sufficient strength, n is greater than 1, morepreferably not less than 1.1, still more preferably not less than 1.2,while it is preferably not more than 5, more preferably not more than 4,still more preferably not more than 3.

Herein, R⁵ is derived from a hydroxy acid or lactone, preferably derivedfrom the above preferable hydroxy acid or lactone such as ethylene,cyclohexylene, phenylene, pentamethylene, and the like.

(Meth)acrylic polymer (III) having a carboxyl group is obtained frompolymerizing (meth)acrylic monomers such as (meth)acrylic acid,(meth)acrylate, these derivatives, and the like, if necessary, there issometimes a case that a copolymer is manufactured in combination withtwo or more (meth)acrylic monomers to be used.

Although (meth)acrylic monomers are not specifically limited, in orderto sufficiently improve initial adhesive strength while suppressingtemporal increase of adhesiveness of a pressure-sensitive adhesive layerhaving sufficient strength, the (meth)acrylic monomer may be, forexample, (meth)acrylic esters such as methyl(meth)acrylate,ethyl(meth)acrylate, propyl(meth)acrylate, butyl(meth)acrylate,hexyl(meth)acrylate, octyl(meth)acrylate, 2-ethylhexyl(meth)acrylate,decyl(meth)acrylate, dodecyl(meth)acrylate, lauryl(meth)acrylate,lauryl-dodecyl(meth)acrylate, tridecyl(meth)acrylate,cetyl-stearyl(meth)acrylate, stearyl(meth)acrylate,cyclohexyl(meth)acrylate, benzyl(meth)acrylate, and phenyl methacrylate;acrylic monomers having a carboxyl group such as (meth)acrylic acid;(meth)acrylic amides such as (meth)acrylic amide and (meth)acrylicmethylolamide; reactive acrylic monomers such ashydroxyethyl(meth)acrylate, hydroxypropyl(meth)acrylate,hydroxybutyl(meth)acrylate, dimethylaminoethyl(meth)acrylate,diethylaminoethyl(meth)acrylate, butylaminoethyl(meth)acrylate,glycidyl(meth)acrylate, and tetrahydrofurfuryl(meth)acrylate;crosslinking acrylic monomers such as ethylene di(meth)acrylate,diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate,tetraethylene glycol di(meth)acrylate, decaethylene glycoldi(meth)acrylate, pentadecaethylene glycol di(meth)acrylate,pentacontahectaethylene glycol di(meth)acrylate, butylenedi(meth)acrylate, allyl(meth)acrylate, trimethylolpropanetri(meth)acrylate, pentaerythritol tetra(meth)acrylate, anddiethyleneglycol di(meth)acrylate phthalate. Preferably the(meth)acrylic monomer is alkyl(meth)acrylate and (meth)acrylic acid.

Further, a monomer which is copolymerizable with the (meth)acrylicmonomers as described above and introduces a monomer wherein a carboxylgroup and a (meth)acryloyl group into the (meth)acrylic polymer (III)may be copolymerized. As a monomer introducing a carboxyl group, may beused alkenyl carboxylic acids such as vinyl acetate, allyl acetate, andthe like; and alkenyl(meth)acrylates such as vinyl (meth)acrylate,allyl(meth)acrylate, and the like.

Further, a group having a carboxyl group at the terminal of the(meth)acrylic polymer (III) may be introduced and also a group having a(meth)acryloyl group may be introduced.

As the (meth)acrylic polymer (III) as described above, the followinggeneral formula (III) may be illustrated.

wherein m_(i) is m_(l)-m_(l) corresponding to one repeat structure unit;l is an integer of not less than 1; m_(i) is independently each aninteger or a real number of not less than 1; R⁶, R^(8i) and R¹⁰ areindependently each hydrogen or a methyl group; L⁷ is a group containinga carboxyl group, a group containing a (meth)acryloyl group or —CO₂R⁷ inwhich R⁷ is hydrogen or a hydrocarbon group of 1-20 carbons; L^(9i) is agroup containing a carboxyl group, a group containing a (meth)acryloylgroup or —CO₂R^(9i) in which R^(9i) is hydrogen or a hydrocarbon groupof 1-20 carbons; L¹¹ is a group containing a carboxyl group, a groupcontaining a (meth)acryloyl group or —CO₂R¹¹ in which R¹¹ is hydrogen ora hydrocarbon group of 1-20 carbons; X¹ and X² are independently eachhydrogen, a group containing a carboxyl group or a group containing a(meth)acryloyl group; and any of R⁷, L^(9i) and L¹¹ does not contain acarboxyl group, or when any of R⁷, L^(9i) and L¹¹ is not hydrogen, atleast one of either X¹ or X² contains a carboxyl group. Specificallywhen there is distribution of a polymerization degree of a repeatstructure unit containing L^(9i), m_(i) is intended to represent thenumber-average polymerization degree which is not always an integer.

In order to sufficiently improve initial adhesive strength whilesuppressing temporal increase of adhesiveness of a pressure-sensitiveadhesive layer having sufficient strength, the weight-average molecularweight is preferably not less than 1,000, more preferably not less than1,500, while it is preferably not more than 10,000, more preferably notmore than 5,000.

Specific examples of carboxyl group-containing acrylic compounds asdescribed above may include those which have: a main chain skeletonhaving a low glass transition temperature; a carboxyl group in amolecule, at least any one of a (meth)acryloyl group and a carboxylgroup on at least any of a molecular terminal and a side chain, a mainchain skeleton consisting of a copolymer of an ethyl(meth)acrylate and alauryl(meth)acrylate, a carboxyl group on at least any of a molecularterminal and a side chain, and the like such as the copolymerized onesof two or more of: ethylene oxide-modified succinic acid (meth)acrylate(CH₂═CH—CO—OC₂H₄O—CO—C₂H₄—CO₂H, CH₂═CCH₃—CO—OC₂H₄O—CO—C₂H₄—CO₂H),2-(meth)acryloyloxyethyl phthalate (CH₂═CH—CO—OC₂H₄O—CO-φ-CO₂H,CH₂═CCH₃—CO—OC₂H₄O—CO-φ-CO₂H wherein φ is a 1,2-phenylene group),2-(meth)acryloyloxyethyl tetrahydrophthalate, 2-(meth)acryloyloxyethylhexahydrophthalate (CH₂═CH—CO—OC₂H₄O—CO-ch-CO₂H,CH₂═CCH₃—CO—OC₂H₄O—CO-ch-CO₂H wherein ch is a 1,2-cyclohexylene group),2-(meth)acryloyl oxypropyl phthalate (CH₂═CH—CO—OC₃H₆O—CO-φ-CO₂H,CH₂═CCH₃—CO—OC₃H₆O—CO-φ-CO₂H wherein φ is a 1,2-phenylene group), aspreferable ester form (I); β-carboxyethyl(meth)acrylate(CH₂═CH(CO—OC₂H₄)_(n)CO₂H, CH₂═CCH₃(CO—OC₂H₄)_(n)CO₂H wherein n is1.5-3.0), (meth)acryloyl oligoester (CH₂═CH—CO—O(C₂H₄—CO₂)_(n)H,CH₂═CCH₃—CO—O(C₂H₄—CO₂)_(n)H wherein n is 1.1-1.7),ω-carboxy-polycaprolactone mono(meth)acrylate(CH₂═CH—CO—O(C₅H₁₀—CO₂)_(n)H, CH₂═CCH₃—CO—O(C₅H₁₀—CO₂)_(n)H wherein n is1.5-3.0), as preferable ester form (II); and ethyl(meth)acrylate,butyl(meth)acrylate, 2-ethylhexyl(meth)acrylate and lauryl(meth)acrylateas (meth)acrylic polymer (III).

Further, if necessary, two or more of carboxyl acid-containing acryliccompounds as described above may be used together.

An addition amount of the carboxyl acid-containing acrylic compound isset carefully considering performance of the obtained adhesivecomposition and adhesive layer: to 100 parts by weight of a radiationsetting compound, preferably not less than 1 part by weight, morepreferably not less than 3 parts by weight, and still more preferablynot less than 5 parts by weight, while it is preferably not more than 80parts by weight, more preferably not more than 30 parts by weight, andstill more preferably not more than 10 parts by weight.

Adhesive Composition

Using natural rubber based particles as described above and a radiationsetting medium such as a radiation setting acrylic compound(hereinafter, if necessary, also referred to as the first acryliccompound) as described above and a radiation setting compound containingcyclic ether, a method for preparing an adhesive composition will bedescribed using FIG. 1.

First, as shown in FIG. 1(a), to radiation setting medium 32 is addedaqueous emulsion 31 containing 40-80 wt % of natural rubber basedparticles 30.

This is mixed and the mixture 33 is heated using, for example, warm bath34 as shown in FIG. 1(b). By heating, water which is an aqueous emulsionmedium is vaporized to be gradually removed out of the mixture. And aswater reduced, the water as the dispersion medium is replaced with theradiation setting medium (FIG. 1(c)).

When doing this method actually, as water reduces, viscosity of themixture increases, while when the dispersion medium is replaced,viscosity of the mixture is suddenly reduced. Change of such suddenchange of viscosity is thought to be caused by phase transition, and byadopting this method, an adhesive composition wherein natural rubberbased particles are dispersed sufficiently and uniformly may be obtainedwithout generating cohesion of the natural rubber based particles, andthe like.

Further, in addition to dispersibility of the natural rubber basedparticles, the natural rubber based particles having a desired averageparticle diameter may be realized from the viewpoint of performance ofthe adhesive composition obtained and adhesive layer. Herein, theaverage particle diameter of the natural rubber based particles ispreferably not less than 0.01 μm, more preferably not less than 0.03 μm,still more preferably not less than 0.05 μm, while it is preferably notmore than 5 μm, more preferably not more than 1 μm, still morepreferably not more than 0.5 μm. The average particle diameter ismeasured based on the weight standard using the light scattering methodand the like.

Further, when adopting the method as described above, the dispersingmedium may be directly replaced without either removing water of themedium from aqueous emulsion containing the natural rubber basedparticles or drying the natural rubber based particles. As a result thewater content of the adhesive composition obtained may be sufficientlylowered, particularly not more than 10 wt %, more preferably not morethan 5 wt %, and still more preferably not more than 1 wt %.

In order to obtain the adhesive composition wherein the natural rubberbased particles having the desired average particle diameter aredispersed sufficiently and uniformly and the water content issufficiently low, the mixing ratio of the aqueous emulsion containingthe natural rubber based particles to the radiation setting mediumshould be carefully selected. Particularly, to 100 parts by weight ofthe aqueous emulsion containing the natural rubber based particles, theratio of the radiation setting medium is set as preferably not less than25 parts by weight, more preferably not less than 40 parts by weight andstill more preferably not less than 50 parts by weight, while it is setas preferably not more than 250 parts by weight preferably not more than150 parts by weight and still preferably not more than 100 parts byweight.

From the similar viewpoint, to 50 parts by weight of the natural rubberbased particles, the ratio of the radiation setting medium is set aspreferably not less than 25 parts by weight, more preferably not lessthan 40 parts by weight and still more preferably not less than 50 partsby weight, while it is set as preferably not more than 250 parts byweight, preferably not more than 150 parts by weight and stillpreferably not more than 100 parts by weight.

Further, in order to obtain the adhesive composition wherein the naturalrubber based particles having the desired average particle diameter aredispersed sufficiently and uniformly and the moisture content issufficiently low, a vaporizing temperature of moisture in the aqueousemulsion containing the natural rubber based particles should becarefully selected. Particularly, it is preferably not less than 20° C.,more preferably not less than 30° C. and still more preferably not lessthan 40° C., while it is preferably not more than 70° C., morepreferably not more than 60° C. and still more preferably not more than50° C.

Furthermore, in order to obtain the adhesive composition wherein thenatural rubber based particles having the desired average particlediameter are dispersed sufficiently and uniformly and the water contentis sufficiently low in a sufficient productivity, a vaporizing method ofthe moisture content in the aqueous emulsion containing the naturalrubber based particles should be carefully selected. Particularly, bysending a warm current of air, reducing in vacuo and the like, thevaporized moisture is forcibly removed to complete a replacement withthe dispersing medium in about 30 min to 5 hrs.

When using a copolymer of natural rubber type rubber with at leasteither an acrylic monomer or a styrene monomer, the copolymer issynthesized prior to replacement with the above dispersing medium.

Such a copolymer may be synthesized by adding either an acrylic monomeror a styrene monomer into natural rubber emulsion, followed by vinylpolymerization of either the acrylic monomer or the styrene monomer inthe natural rubber emulsion.

In this case, the reaction ratio of the natural rubber based particlesto the acrylic monomer and the styrene monomer is set within a range of1-80 parts by weight of the acrylic monomer and the styrene monomer to100 parts by weight of the natural rubber based particles. As apolymerization initiator may be used, for example, those of organicperoxides, preferably redox initiators consisting of organic peroxidesand ethylene diamines, and of them, preferred are redox initiatorsconsisting of t-butylhydroperoxide (t-BHPO) and tetraethylene pentaamine(TEPA). As the organic peroxides, preferred are ketone peroxides, diacylperoxides, dialkyl peroxides, peroxyketals, peroxyesters,peroxycarbonates, and the like, and as ethylene diamines, preferred areethylene diamine (EDA), diethylene triamine (DETA), tetraethyleneteraamine (TETA), pentaethylenehexamine (PEHA), and the like.

The using amount of polymerization initiations is within a range of0.01-10 parts by weight to 100 parts by weight of natural rubber basedparticles.

Further, if necessary, added may be an adhesion-giving agents such asterpene resins, rosin, oil-solublephenol resins, chroman indene resins,petroleum hydrocarbon resins, terpene resin derivatives, rosinderivatives, oil-soluble phenol resin derivatives, chroman indene resinderivatives, petroleum hydrocarbon resin derivatives, and the like.

An emulsion obtained immediately after synthesizing a copolymer asdescribed above contains unreacted monomer and the like besides thecopolymer, however, without purification of the copolymer, a radiationsetting medium may be mixed into the emulsion immediately after itssynthesis followed by being replaced with a dispersing medium.

Moreover, after replaced with the dispersing medium, if necessary, thesecond acrylic compound is added. By using the second acrylic compoundtogether, applicability of the adhesive composition may be controlled ina wider range, higher adhesiveness of the adhesive layer obtained may berealized and higher adhesive strength between the adhesive layer and thesubstrate may be realized.

From such a viewpoint, as the second acrylic compound, preferred areacrylic monomers, or acrylic monomers with 2-10 of the polymerizationdegree, or these mixtures, more particularly, preferred are oligomersobtained from vinyl polymerization of acrylicmonomers, and as theacrylicmonomers, preferred are: (meth)acrylic acid esters such asmethyl(meth)acrylate, ethyl(meth)acrylate, propyl(meth)acrylate,octyl(meth)acrylate, 2-ethylhexyl(meth)acrylate, decyl(meth)acrylate,dodcyl(meth)acrylate, lauryl(meth)acrylate,lauryl-tridecyl(meth)acrylate, tridecyl(meth)acrylate,cetyl-stearyl(meth)acrylate, stearyl(meth)acrylate,cyclohexyl(meth)acrylate, benzyl(meth)acrylate, phenyl(meth)acrylate,and the like; (meth)acrylic acid amides such as (meth)acrylic acidamide, (meth)acrylic acid methylolamide, and the like; reactive acrylicmonomers such as (meth)acrylic acid, hydroxyethyl(meth)acrylate,hydroxypropyl(meth)acrylate, hydroxybutyl(meth)acrylate,dimethylaminoethyl(meth)acrylate, diethylaminoethyl(meth)acrylate,butylaminoethyl(meth)acrylate, glycidyl(meth)acrylate andtetrahydrofufuryl(meth)acrylate, and the like; and crosslinking acrylicmonomers such as ethylene di(meth)acrylate, diethylene glycoldi(meth)acrylate, triethylene glycol di(meth)acrylate, tetraethyleneglycol di(meth)acrylate, decaethylene glycol di(meth)acrylate,pentadecaethylene glycol di(meth)acrylate, pentacontahectaethyleneglycol di(meth)acrylate, butylene glycol di(meth)acrylate, allyldi(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritoltetra(meth)acrylate, and diethylene glycol di(meth)acrylate phthalate,and the like. Two or more of these monomers, if necessary, may be usedtogether, and a mixture of oligomers having different polymerizationdegrees may be also used.

Further, the radiation setting first acrylic compound may be used as thesecond acrylic compound. In this case, like paracumyl phenol EO-reformed(n=1) acrylate, those where an oligomer component of the radiationsetting first acrylic compound is substituted with a monomer componentmay be also used.

Further, an addition amount of the second acrylic compound is carefullyset considering performance of the obtained adhesive composition andadhesive layer: to 100 parts by weight of the radiation setting firstcompound, preferably not less than 1 part by weight, more preferably notless than 3 parts by weight, and still more preferably not less than 5parts by weight, while it is preferably not more than 80 parts byweight, more preferably not more than 30 parts by weight, and still morepreferably not more than 10 parts by weight.

When adding a carboxyl group-containing acrylic compound, it may beadded into a radiation setting medium prior to a replacement step of adispersing medium.

Particularly, an adhesive composition wherein natural rubber basedparticles are uniformly dispersed in a radiation setting compound and acarboxyl group-containing acrylic compound is contained may bemanufactured by a method including steps of:

-   -   mixing an aqueous emulsion containing the natural rubber based        particles and the radiation setting compound;    -   elevating a temperature of the mixture while stirring,        vaporizing water of the aqueous emulsion to be removed, and        replacing the water as the medium where the natural rubber based        particles are dispersed with the radiation setting compound; and        adding the carboxyl group-containing acrylic compound into the        replaced material.

If the carboxyl group-containing acrylic compound is pre-added into theradiation setting compound as described above, adjustments of viscosityof the radiation setting compound and the like may be extensivelyperformed, therefore, replacement of the dispersing medium may beconducted with good workability.

On the other hand, after replacing the dispersing medium, the carboxylgroup-containing acrylic compound may be added into the radiationsetting medium.

Particularly, it may be manufactured by a method including steps of:

-   -   mixing an aqueous emulsion containing the natural rubber based        particles and the radiation setting medium containing the        carboxyl group-containing acrylic compound and the radiation        setting compound; and    -   elevating a temperature of the mixture while stirring,        vaporizing water of the aqueous emulsion to be removed, and        replacing the water as the medium where the natural rubber based        particles are dispersed, with the radiation setting compound.

Described above when adding the carboxyl group-containing acryliccompound after replacement of the dispersed medium, therebydeterioration of the carboxyl group-containing acrylic compound duringthe replacement step may be prevented.

In addition, a part of the carboxyl group-containing acrylic compoundmay be pre-added into the radiation setting medium, then the furthercarboxyl group-containing acrylic compound may be added afterreplacement of the dispersing medium.

When forming the adhesive layer after replacement of the dispersingmedium, if necessary, a polymerization initiator is added to cure theradiation setting medium.

Moreover, in order to improve adhesiveness of the adhesive layerobtained and fixation of the adhesive layer onto the substrate, there issometimes a case that adds styrene-butadiene rubber latex. Thestyrene-butadiene rubber latex is thought to improve adhesion betweenthe substrate applied with the adhesive composition and the naturalrubber based particles.

The styrene-butadiene rubber latex consists of mainly styrene-butadienerubber (SBR), and as SBR may be used emulsion polymerization SBR such asSBR driver and SBR latex; and solution polymerization SBR and the likesuch as random SBR, block SBR and symmetrical block SBR.

Further, characteristics of SBR depend significantly on the copolymerratio of styrene and butadiene. From such a viewpoint, those where thestyrene content is low (not more than 30 wt %), the styrene content ismoderate (more than 30 wt % to not more than 70 wt %), the styrenecontent is high (over 70 wt %) are carefully selected to be used for thestyrene-butadiene rubber latex.

SBR used as a main component of the styrene-butadiene rubber latex mayinclude a non-modified type, a vinylpyridine modified type and a carboxymodified type, and the like. Of them, preferred is carboxy modifiedstyrene-butadiene rubber latex because it is excellent in adhesion to asubstrate and adhesiveness between the natural rubber based particlesand the substrate may be sufficiently improved.

In order to sufficiently improve adhesiveness of the natural rubberbased particles, the mixing ratio of the styrene-butadiene rubber latexto the natural rubber based particles is preferably not less than 1 partby weight, more preferably not less than 5 parts by weight of thestyrene-butadiene rubber latex to 100 parts by weight of the naturalrubber based particles. On the other hand, in order not to lose othercharacteristics of the natural rubber based particles, the ratio ispreferably not more than 50 parts by weight, more preferably not morethan 30 parts by weight and still more preferably not more than 20 partsby weight.

Also, since sufficient interaction between the adhesive layer obtainedand printing agents including ink and toner, etc. may be realized bysetting the content of the styrene-butadiene rubber latex as anappropriate value, sufficient fixation of the printing agents may berealized. Further, since adhesive strength after pressing adhesion layermay be made to be appropriate, detachment of the adhesive layer atunnecessary time after pressuring adhesion may be suppressed, while ifnecessary, the adhesive layer may be readily detached at desired timeafter pressing adhesion.

Further, in order to realize sufficient blocking resistance of thepressure-sensitive adhesive composition obtained, preferably a fillerwhich is non-affinitive to the natural rubber based particles is addedinto the adhesive composition. Since unevenness on the surface of theadhesive layer (adhesive surface) is formed by addition of the filler,suppressed is adhesion of the adhesive surface to the other surfaceprior to pressing adhesion on the adhesive surface, and it is thought toimprove blocking resistance.

In addition, if unevenness on the surface of the adhesive layer(adhesive surface) is formed by addition of the filler, melt adhesionbetween the adhesive surfaces after pressing adhesion proceeds and it isconsidered that temporal increase of adhesiveness may be suppressed. Asthese results, if it is necessary to detach the adhesive surface afterpressing adhesion, the adhesive surface may be readily detached.

Also, if it is necessary to become so as not to inhibit transparency ofthe adhesive layer, preferred are those wherein the particle form as afiller is regularly arranged. Such materials include, for example,different silica fillers, different starch fillers, synthetic zeolite,microspherical (meth)acrylic resins, microspherical polyethylene,spherical alumina, glass powder, silus balloon, activated clay, titaniumoxide and zinc oxide, and the like. These fillers may be used alone orin combination with two or more of them.

Herein, the average particle diameter of these fillers is preferably notless than 0.01 μm and more preferably not less than 1 μm, while it ispreferably not more than 35 μm and more preferably not more than 25 μm.Further, when using in combination with two or more of differentparticle diameters, its combination is likely to unevenly form thesurface of the adhesive layer and therefore advantageous to blockingresistance and improvement of detachment performance.

Of the above fillers, the silica filler and starch filler are preferablebecause they have less affinity to the natural rubber based particlesand may realize sufficient blocking resistance.

In case of the silica filler, to 100 parts by weight of the naturalrubber based particles, a combination amount of the filler is preferablynot less than 10 parts by weight, more preferably not less than 20 partsby weight, and still more preferably not less than 30 parts by weight,while it is preferably not more than 100 parts by weight, morepreferably not more than 80 parts by weight, and still more preferablynot more than 60 parts by weight.

Also, in case of the starch filler, to 100 parts by weight of thenatural rubber based particles, a combination amount of the filler ispreferably not less than 10 parts by weight, more preferably not lessthan 20 parts by weight, and still more preferably not less than 30parts by weight, while it is preferably not more than 200 parts byweight, more preferably not more than 180 parts by weight, and stillmore preferably not more than 160 parts by weight.

In addition to the above additives, in order to improve ultravioletresistance, there is sometimes a case where an ultraviolet absorbingagent (ultraviolet absorbent) is added into the adhesive composition.

Such ultraviolet absorbents may include: salicylic acids such as phenylsalicylate, butylphenyl salicylate, octylphenyl salicylate, and thelike; benzophenones such as dihydroxybenzophenone,hydroxymethoxybenzophenone, hydroxyocthoxybenzophenone,hydroxydodecyloxybenzophenone, hydroxymethoxysulfobenzophenone,bis(methoxyhydroxybenzoylphenyl)methane, and the like; benzotriazolessuch as (hydroxymethylphenyl)benzotriazole,(hydroxybutylphenyl)benzotriazole, (hydroxydibutylphenyl)benzotriazole,(hydroxybutylmethylphenyl)chlorobenzotriazole,(hydroxydibutylphenyl)chlorobenzotriazole,(hydroxydiamylphenyl)benzotriazole and[hydroxy(tetrahydrophthalimidemethyl)methylphenyl]bennzot riazole, andthe like; cyanoacrylates such as ethylhexylcyanodiphenyl acrylate,ethylcyanodiphenyl acrylate, and the like; and hindered amins and thelike.

Also, there is sometimes a case that needs antioxidants. As theantioxidants may be used: amines including aromatic secondary aminessuch as amine-ketones, diphenylamines, diaryl-P-phenylenediamins,alkylaryl-P-phenylenediamines, and the like; phenols includingmonophenols, bisphenols and hydroquinones; organic sulfurs; phosphites;and these complex systems, and the like, of them, phenols are preferablebecause they give less pollution and coloration.

Furthermore, the adhesive composition, if necessary, may be made incombination with synthetic rubber emulsions. The synthetic rubberemulsions may illustrate emulsions dispersed in aqueous solvents withsynthetic rubber such as polyisobutylene rubber, polybutadiene rubber,acrylonitrile-butadiene rubber, methyl methacrylate-butadiene rubber,chloroprene rubber, butyl rubber, polyurethane rubber, thiocoal rubberand acrylic rubber, and the like.

The adhesive composition may be made also in combination with syntheticresin emulsions. The synthetic resin emulsions may illustrate vinylpolyacetate emulsions, vinyl acetate-ethylene copolymer emulsions,polyacrylic acid ester emulsions and vinyl polychloride emulsions, andthe like. Herein, of these synthetic resin emulsions, those wherein theglass transition temperature (Tg) is −30 to 20° C. are suitable.

Emulsifiers maybe added in order to stabilize dispersion of the naturalrubber based particles. Such emulsifiers may use anionic and nonionicsurfactants such as rosin soap, naphthalene sulfonic acid salts,aliphatic acid soap and alkylbenzene sulfonic acid salts, and the like.

Furthermore, if necessary, to the adhesive composition may be mixed pHadjusting agents, antioxidants, adhesive-giving agents, viscosityadjusting agents, rubber antioxidants, stabilizers and coloring agents,and the like.

Sheet for Carrying Information

The adhesive composition obtained such as described above is applied ona substrate using application means of a photogravure coater, a flex, anair knife coater, a wire bar and a bar coater, and the like, to form afilm.

Further, the substrate has forms such as a sheet form, and may usebesides usual paper, synthetic films such as synthetic paper,polyethylene, polyethylene terephthalate, polypropylene and vinylchloride, and the like. When using these synthetic films, preferablyperformed is surface treatment such as mat treatment and coronatreatment, the like on the surface of a substrate sheet.

Also, in order to maintain adhesion, detachment and transparency, anapplication amount of the adhesive composition onto the sheet surface ofthe substrate is preferably not less than 1 g/m², more preferably notless than 3 g/m² and still more preferably not less than 4 g/m², whileit is preferably not more than 30 g/m², more preferably not more than 20g/m² and still more preferably not more than 7 g/m².

A film consisting of the adhesive composition is cured by irradiatingradiation. As a result, as shown in FIG. 2, the pressure-sensitiveadhesive layer is formed on the sheet of substrate 42, and thepressure-sensitive adhesive layer may give a sheet for carryinginformation which is radiation cured material 41 of the radiationsetting medium wherein natural rubber based particles 40 are dispersed.Further, it is considered that a part of the radiation setting mediumwhich is a dispersing medium is dispersed in the substrate beforecuring. As shown in 43, it is considered that a part of the radiationsetting medium is cured in the substrate or reacted with the substrateby irradiating radiation. As a result, high adhesive strength betweenthe adhesive layer and the substrate may be realized.

Also, the film, if necessary, is dried before curing, however, duringthe curing process by irradiation of radiation, the drying proceedssimultaneously. Since the dispersing medium is the radiation settingmedium, the drying may be completed in a short time or there issometimes a case that does not need separately the drying process.

Herein, examples wherein the adhesive layer is a detachable sheet forcarrying information and the adhesive layer is an undetachable sheet forcarrying information are shown in FIG. 3(a) and FIG. 4(a), respectively.

In case of FIG. 3(a), as shown in FIG. 3(b), information 12 such asconcealment and confidentiality and the like is printed on adhesivelayer 10. Thereafter,as shown in FIG. 3(c), the sheet for carryinginformation is folded down at folding line 11 so that the adhesive layer10 is layered, then pressing adhesion is performed on adhesive layer 10.And as shown in FIG. 3(d), when necessary, adhesive layer 10 is detachedto read information 12. In this case, the adhesive layer is required forbeing readily detachable at desired time after pressing adhesion.Further, the adhesive composition is applied overall.

On the other hand, in case of FIG. 4(a), as shown in FIG. 4(b),information 22 of concealment and confidentiality is printed at theposition without forming of adhesive layer 20. Thereafter, as shown inFIG. 4(c), the sheet for carrying information is folded down at foldingline 21 so that adhesive layer 10 is layered, then pressing adhesion onadhesive layer 20. And as shown in FIG. 4(d), reading of information 22without detaching adhesive layer 20 is performed by cutting theprescribed position (for example, perforating line 23 of the substratesheet and the like. In this case, the adhesive layer is required for notbeing detached substantially after pressing adhesion. Further, theadhesive composition is applied in pattern.

Also, by changing a combination ratio of the material comprising thepressure-sensitive adhesive composition and the pressing adhesioncondition, the adhesive layer may be either detachable or undetachable.

When the adhesive layer is detachable, necessary information is printedor typed on the adhesive layer obtained. Printing methods may adoptbesides usual printing machine, an electrophotography method, and typingmethods may adopt an ink jet method and the like. In case of the ink jetmethod, a printing agent is ink, and in case of the electrophotographymethod, a printing agent is toner. Thereafter, to dry and/or fix theirprinting agents, ultraviolet rays are irradiated. Also, to dry and/orfix their printing agents, there is sometimes a case of heating.

The sheet for carrying information described above may be bonded informs of folding in two, folding in three, cut folding and in differentlayering forms, and may be suitably utilized as postcards having twofacing surfaces, different business forms, notices and different cards.

Although the present invention will be described particularly by thefollowing Examples and Comparative Examples, the present invention isnot limited to the following Examples. Unless otherwise specified, forchemicals etc., used are commercially available highly pure products.

Preparation of Natural Rubber Emulsion of Acrylic-Styrene Copolymer

To 200 parts by weight of aqueous emulsion containing 100 parts byweight of natural rubber latex was mixed 10 parts by weight of styreneand 25 parts by weight of methyl methacrylate, followed by adding 0.1parts by weight of t-butylhydroperoxide (t-BHPO) and 0.3 parts by weightof tetraethylenepentamine (TEPA) as polymerization initiators. To thecopolymer natural rubber emulsion obtained from reacting this mixture at45° C./in nitrogen atmosphere for 2 hours, 5 parts by weight of terpeneresin as an adhesion-giving agent were added to give aqueous emulsioncontaining natural rubber based particles.

EXAMPLE 1-1 Adhesive Composition 1-1 And Sheet for Carrying Information1-1

In order to be adjusted to 100 parts by weight to 100 parts by weight ofnatural rubber based particles, polyethylene glycol diacrylate (tradename: ARONIX M-240, from TOAGOSEI CO., LTD.) was added to the aqueousemulsion containing natural rubber based particles obtained above andwell stirred, thereafter, by elevating the mixture at 50° C. followed byremoval of moisture vaporized in vacuo to substitute the dispersedmedium in 1 hr. Herein, the weight ratio of aqueous emulsion containingnatural rubber based particles to polyethylene glycol diacrylate was160:100.

To this was added 4 parts by weight of the photopolymerization initiator(trade name: VICURE 55, from Akzo Nobel) to afford ultraviolet curingtype pressure-sensitive adhesive composition 1-1.

When measured the moisture content of pressure-sensitive adhesivecomposition 1-1 obtained, it was 0.5 wt %. The average particle diameterof the natural rubber based particles was 0.2 μm and the dispersibilitywas uniform.

The pressure-sensitive adhesive composition 1-1 was applied in order to6 g/m² on form high-quality paper (trade name: NIP N (70 kg rangeamount) from Oji Paper Co., Ltd.) using a wire bar, followed by beingcured using high-pressure mercury lamp to form the adhesive layer and togive sheet for carrying information 1-1. The applicability also in thecases of whole application and pattern application was well similarly tothe case of low absorbable paper. There was no generation of poor statessuch as poor drying and the like.

After layered together with two surfaces forming the adhesive layer ofsheet for carrying information 1-1 obtained, a sealing machine was setto 100 μm of a gap between rollers to do sealing. After sealing, twoforms adhered with sufficient strength. When detached these two forms,they could be finely detached without detachment between the adhesivelayer and the substrate.

EXAMPLE 1-2 Adhesive Composition 1-2 And Sheet for Carrying Information1-2

The similar operation was performed except changing the using amount ofpolyethylene glycol diacrylate used in adhesive composition 1-1 to 60parts by weight to give adhesive composition 1-2 and sheet for carryinginformation 1-2. The adhesive composition 1-2 and sheet for carryinginformation 1-2 obtained had practically durable performance.

EXAMPLE 1-3 Adhesive Composition 1-3 And Sheet for Carrying Information1-3

In order to be adjusted to 100 parts by weight to 100 parts by weight ofnatural rubber based particles, polyethylene glycol diacrylate (tradename: ARONIX M-240, from TOAGOSEI CO., LTD.) was added to the aqueousemulsion containing natural rubber based particles used in adhesivecomposition 1-1 and well stirred, thereafter, by elevating the mixtureat 50° C. followed by removal of moisture vaporized in vacuo tosubstitute the dispersed medium in 1 hr. Herein, the weight ratio ofaqueous emulsion containing natural rubber based particles topolyethylene glycol diacrylate was 160:100.

On the other hand, in 100 parts by weight of acrylic dimer (trade name:ARONIX M-5600, from TOAGOSEI CO., LTD.) was dissolved 100 parts byweight of the photopolymerization initiator (trade name: VICURE 55, fromAkzo Nobel), followed by adding this 10 parts by weight into the abovedispersed medium substituent to afford ultraviolet curing typepressure-sensitive adhesive composition 1-3.

When measured the moisture content of pressure-sensitive adhesivecomposition 1-3 obtained, it was 0.5 wt %. The average particle diameterof the natural rubber based particles was 0.2 μm and the dispersibilitywas uniform.

The pressure-sensitive adhesive composition 1-3 was applied in order tobecome 6 g/m² on form high-quality paper (trade name: NIP N (70 kg rangeamount) from Oji Paper Co., Ltd.) using a wire bar, followed by beingcured using high-pressure mercury lamp to form the adhesive layer and togive sheet for carrying information 1-3. The applicability also in thecases of whole application and pattern application was well similarly tothe case of low absorbable paper. There was no generation of poor statessuch as poor drying and the like.

After layered together with two surfaces forming the adhesive layer ofsheet for carrying information 1-3 obtained, a sealing machine was setto 60 μm of a gap between rollers to do sealing. After sealing, twoforms adhered with sufficient strength. When detached these two forms,they could be finely detached without detachment between the adhesivelayer and the substrate.

EXAMPLE 1-4 Adhesive Composition 1-4 And Sheet for Carrying Information1-4

The similar operation was performed except changing acrylic dimer usedin adhesive composition 1-3 to nonylphenol EO-reformed (n=4) acrylate(ARONIX M-113, from TOAGOSEI CO., LTD.) to give adhesive composition1-4. Further, except setting a sealing machine to 100 μm of a gapbetween rollers, the operation similar to sheet for carrying information1-3 was performed to obtain sheet for carrying information 1-4. Theadhesive composition 1-4 and sheet for carrying information 1-4 obtainedhad good performance.

EXAMPLE 1-5 Adhesive Composition 1-5 And Sheet for Carrying Information1-5

The similar operation was performed except changing acrylic dimer usedin adhesive composition 1-3 to paracumylphenol EO-reformed (n=1)acrylate (ARONIX M-110, from TOAGOSEI CO., LTD.) to give adhesivecomposition 1-5. Further, except setting a sealing machine to 100 μm ofa gap between rollers, the operation similar to sheet for carryinginformation 1-3 was performed to obtain sheet for carrying information1-5. The adhesive composition 1-5 and sheet for carrying information 1-5obtained had good performance.

EXAMPLE 1-6 Adhesive Composition 1-6 And Sheet for Carrying Information1-6

To 100 parts by weight of natural rubber based particles in adhesivecomposition 1-3, in order to set from Takeda Chemical Industries, Ltd.SBR (trade name: CROSLENE SK-72) as 15 parts by weight, in order to setcommercially available silica of average particle diameter 4 μm as 50parts by weight and in order to set commercially available wheat starchof average particle diameter 15 μm as 150 parts by weight, the similaroperation was performed except adding these fillers to obtain adhesivecomposition 1-6. The operation similar to the case of sheet for carryinginformation 1-5 was performed to obtain sheet for carrying information1-6. The adhesive composition 1-6 and sheet for carrying information 1-6obtained had good performance.

EXAMPLE 1-7 Adhesive Composition 1-7 And Sheet for Carrying Information1-7

In order to be adjusted to 100 parts by weight to 100 parts by weight ofnatural rubber based particles, 70 parts by weight of polyethyleneglycol diacrylate (trade name: ARONIX M-240, from TOAGOSEI CO., LTD.)and 30 parts by weight of trimethylol propane EO added triacrylate(trade name: Viscoat #360, from OSAKA ORGANIC CHEMICAL INDUSTRY LTD.)were added to the aqueous emulsion containing natural rubber basedparticles used in adhesive composition 1-1 and well stirred, thereafter,by elevating the mixture at 50° C. followed by removal of moisturevaporized in vacuo to substitute the dispersed medium in 1 hr. Herein,the weight ratio of aqueous emulsion containing natural rubber basedparticles to polyethylene glycol diacrylate and trimethylol propane EOadded triacrylate was 160:100.

To this was added 4 parts by weight of the photopolymerization initiator(trade name: VICURE 55, from Akzo Nobel) to afford ultraviolet curingtype pressure-sensitive adhesive composition 1-7.

When measured the moisture content of pressure-sensitive adhesivecomposition 1-7 obtained, it was 0.5 weight %. The average particlediameter of the natural rubber based particles was 0.2 μm and thedispersibility was uniform.

The pressure-sensitive adhesive composition 1-7 was applied in order tobecome 6 g/m² on form high-quality paper (trade name: NIP N (70 kg rangeamount) from Oji Paper Co., Ltd.) using a wire bar, followed by beingcured using high-pressure mercury lamp to form the adhesive layer and togive sheet for carrying information 1-7. The applicability also in thecases of whole application and pattern application was well similarly tothe case of low absorbable paper. There was no generation of poor statessuch as poor drying and the like.

After layered together with two surfaces forming the adhesive layer ofsheet for carrying information 1-7 obtained, a sealing machine was setto 100 μm of a gap between rollers to do sealing. After sealing, twoforms adhered with sufficient strength. When detached these two forms,they could be finely detached without detachment between the adhesivelayer and the substrate.

COMPARATIVE EXAMPLE 1-1

In 100 parts by weight of polyethylene glycol diacrylate (trade name:ARONIX M-240, from TOAGOSEI CO., LTD.) was dissolved 8 parts by weightof the photopolymerization initiator (trade name: VICURE 55, from AkzoNobel). The obtained solution was applied in order to become 6 g/m² onform high-quality paper (trade name: NIP N (70 kg range amount) from OjiPaper Co., Ltd.) using a wire bar, followed by being cured usinghigh-pressure mercury lamp. After layered together with two adhesivesurfaces of applied paper obtained, a sealing machine was set to 100 μmof a gap between rollers to do sealing, however, two forms after sealingdid not adhere to each other.

COMPARATIVE EXAMPLE 1-2

Commercially available ultraviolet curing type acrylicpressure-sensitive false adhesive was applied in order to become 6 g/m²on form high-quality paper (trade name: NIP N (70 kg range amount) fromOji Paper Co., Ltd.) using a wire bar, followed by being cured usinghigh-pressure mercury lamp. After layered together with two adhesivesurfaces of applied paper obtained, a sealing machine was set to 100 μmof a gap between rollers to do sealing, however, two forms after sealingdid not adhere to each other.

EXAMPLE 2-1 Adhesive Composition 2-1 And Sheet for Carrying Information2-1

In order to be adjusted to 100 parts by weight to 100 parts by weight ofnatural rubber based particles, ethylene glycol diglycidyl ether (tradename: Epolite 400E, from KYOEISHA CHEMICAL Co., LTD.) was added to theaqueous emulsion containing natural rubber based particles obtainedpreviously and well stirred, thereafter, by elevating the mixture at 50°C. followed by removal of moisture vaporized in vacuo to substitute thedispersed medium in 1 hr. Herein, the weight ratio of aqueous emulsioncontaining natural rubber based particles to ethylene glycol diglycidylether was 160:100.

To this was added 4 parts by weight of the photopolymerization initiator(trade name: VICURE 55, from Akzo Nobel) to afford ultraviolet curingtype pressure-sensitive adhesive composition 2-1. When measured themoisture content of pressure-sensitive adhesive composition 2-1obtained, it was 0.5 wt %. The average particle diameter of the naturalrubber based particles was 0.2 μm and the dispersibility was uniform.

The pressure-sensitive adhesive composition 2-1 was applied in order tobecome 6 g/m² on form high-quality paper (trade name: NIP N (70 kg rangeamount) from Oji Paper Co., Ltd.) using a wire bar, followed by beingcured using high-pressure mercury lamp to form the adhesive layer and togive sheet for carrying information 2-1. The applicability also in thecases of whole application and pattern application was well similarly tothe case of low absorbable paper. There was no generation of poor statessuch as poor drying and the like.

After layered together with two surfaces forming the adhesive layer ofsheet for carrying information 2-1 obtained, a sealing machine was setto 100 μm of a gap between rollers to do sealing. After sealing, twoforms adhered with sufficient strength. When detached these two forms,they could be finely detached without detachment between the adhesivelayer and the substrate.

EXAMPLE 2-2 Adhesive Composition 2-2 And Sheet for Carrying Information2-2

The similar operation was performed except changing the using amount ofethylene glycol diglycidyl ether used in adhesive composition 2-1 to 60parts by weight to give adhesive composition 2-2 and sheet for carryinginformation 2-2. The adhesive composition 2-2 and sheet for carryinginformation 2-2 obtained had practically durable performance.

EXAMPLE 2-3 Adhesive Composition 2-3 And Sheet for Carrying Information2-3

In order to be adjusted to 100 parts by weight to 100 parts by weight ofnatural rubber based particles, ethylene glycol diglycidyl ether (tradename: Epolite 400E, from KYOEISHA CHEMICAL Co., LTD.) was added to theaqueous emulsion containing natural rubber based particles used inadhesive composition 2-1 and well stirred, thereafter, by elevating themixture at 50° C. followed by removal of moisture vaporized in vacuo tosubstitute the dispersed medium in 1 hr. Herein, the weight ratio ofaqueous emulsion containing natural rubber based particles to ethyleneglycol diglycidyl ether was 160:100.

On the other hand, in 100 parts by weight of acrylic dimer (trade name:ARONIX M-5600, from TOAGOSEI CO., LTD.) was dissolved 100 parts byweight of the photopolymerization initiator (trade name: VICURE 55, fromAkzo Nobel), followed by adding this 10 parts by weight into the abovedispersed medium substituent to afford ultraviolet curing typepressure-sensitive adhesive composition 2-3.

When measured the moisture content of pressure-sensitive adhesivecomposition 2-3 obtained, it was 0.5 wt %. The average particle diameterof the natural rubber based particles was 0.2 μm and the dispersibilitywas uniform.

The pressure-sensitive adhesive composition 2-3 was applied in order tobecome 6 g/m² on form high-quality paper (trade name: NIP N (70 kg rangeamount) from Oji Paper Co., Ltd.) using a wire bar, followed by beingcured using high-pressure mercury lamp to form the adhesive layer and togive sheet for carrying information 2-3. The applicability also in thecases of whole application and pattern application was well similarly tothe case of low absorbable paper. There was no generation of poor statessuch as poor drying and the like.

After layered together with two surfaces forming the adhesive layer ofsheet for carrying information 2-3 obtained, a sealing machine was setto 60 μm of a gap between rollers to do sealing. After sealing, twoforms adhered with sufficient strength. When detached these two forms,they could be finely detached without detachment between the adhesivelayer and the substrate.

EXAMPLE 2-4 Adhesive Composition 2-4 And Sheet for Carrying Information2-4

The similar operation was performed except changing acrylic dimer usedin adhesive composition 2-3 to nonylphenol EO-reformed (n=4) acrylate(ARONIX M-113, from TOAGOSEI CO., LTD.) to give adhesive composition2-4. Further, except setting a sealing machine to 100 μm of a gapbetween rollers, the operation similar to sheet for carrying information2-3 was performed to obtain sheet for carrying information 2-4. Theadhesive composition 2-4 and sheet for carrying information 2-4 obtainedhad good performance.

EXAMPLE 2-5 Adhesive Composition 2-5 And Sheet for Carrying Information2-5

The similar operation was performed except changing acrylic dimer usedin adhesive composition 2-3 to paracumylphenol EO-reformed (n=1)acrylate (ARONIX M-110, from TOAGOSEI CO., LTD.) to give adhesivecomposition 2-5. Further, except setting a sealing machine to 100 μm ofa gap between rollers, the operation similar to sheet for carryinginformation 2-3 was performed to obtain sheet for carrying information2-5. The adhesive composition 2-5 and sheet for carrying information 2-5obtained had good performance.

EXAMPLE 2-6 Adhesive Composition 2-6 And Sheet for Carrying Information2-6

To 100 parts by weight of natural rubber based particles in adhesivecomposition 2-3, in order to set from Takeda Chemical Industries, Ltd.SBR (trade name: CROSLENE SK-72) as 15 parts by weight, in order to setcommercially available silica of average particle diameter 4 μm as 50parts by weight and in order to set commercially available wheat starchof average particle diameter 15 μm as 150 parts by weight, the similaroperation was performed except adding these fillers to obtain adhesivecomposition 2-6. The operation similar to the case of sheet for carryinginformation 2-5 was performed to obtain sheet for carrying information2-6. The adhesive composition2-6 and sheet for carrying information 2-6obtained had good performance.

EXAMPLE 2-7 Adhesive Composition 2-7 And Sheet for Carrying Information2-7

In order to be adjusted to 100 parts by weight to 100 parts by weight ofnatural rubber based particles, 75 parts by weight of ethylene glycoldiglycidyl ether (trade name: Epolite 400E, from KYOEISHA CHEMICAL Co.,LTD.) and 25 parts by weight of trimethylol propane triglycidyl ether(trade name: Epolite 100MF, from KYOEISHA CHEMICAL Co., LTD.) were addedto the aqueous emulsion containing natural rubber based particles usedin adhesive composition 2-1 and well stirred, thereafter, by elevatingthe mixture at 50° C. followed by removal of moisture vaporized in vacuoto substitute the dispersed medium in 1 hr. Herein, the weight ratio ofaqueous emulsion containing natural rubber based particles to ethyleneglycol diglycidyl ether and trimethylol propane triglycidyl ether was160:100.

To this was added 4 parts by weight of the photopolymerization initiator(trade name: VICURE 55, from Akzo Nobel) to afford ultraviolet curingtype pressure-sensitive adhesive composition 2-7.

When measured the moisture content of pressure-sensitive adhesivecomposition 2-7 obtained, it was 0.5 wt %. The average particle diameterof the natural rubber based particles was 0.2 μm and the dispersibilitywas uniform.

The pressure-sensitive adhesive composition 2-7 was applied in order tobecome 6 g/m² on form high-quality paper (trade name: NIP N (70 kg rangeamount) from Oji Paper Co., Ltd.) using a wire bar, followed by beingcured using high-pressure mercury lamp to form the adhesive layer and togive sheet for carrying information 2-7. The applicability also in thecases of whole application and pattern application was well similarly tothe case of low absorbable paper. There was no generation of poor statessuch as poor drying and the like.

After layered together with two surfaces forming the adhesive layer ofsheet for carrying information 2-7 obtained, a sealing machine was setto 100 μm of a gap between rollers to do sealing. After sealing, twoforms adhered with sufficient strength. When detached these two forms,they could be finely detached without detachment between the adhesivelayer and the substrate.

COMPARATIVE EXAMPLE 2-1

In 100 parts by weight of ethylene glycol diglycidyl ether (trade name:Epolite 400E, from KYOEISHA CHEMICAL Co., LTD.) was dissolved 8 parts byweight of the photopolymerization initiator (trade name: VICURE 55, fromAkzo Nobel). The obtained solution was applied in order to become 6 g/m²on form high-quality paper (tradename: NIP N (70 kg range amount) fromOji Paper Co., Ltd.) using a wire bar, followed by being cured usinghigh-pressure mercury lamp. After layered together with two adhesivesurfaces of applied paper obtained, a sealing machine was set to 100 μmof a gap between rollers to do sealing, however, two forms after sealingdid not adhere to each other.

COMPARATIVE EXAMPLE 2-2

Commercially available ultraviolet curing type acrylicpressure-sensitive false adhesive was applied in order to become 6 g/m²on form high-quality paper (trade name: NIP N (70 kg range amount) fromOji Paper Co., Ltd.) using a wire bar, followed by being cured usinghigh-pressure mercury lamp. After layered together with two adhesivesurfaces of applied paper obtained, a sealing machine was set to 100 μmof a gap between rollers to do sealing, however, two forms after sealingdid not adhere to each other.

EXAMPLE 3-1 Adhesive Composition 3-1 And Sheet for Carrying Information3-1

In order to be adjusted to 100 parts by weight to 100 parts by weight ofnatural rubber based particles, polyethylene glycol diacrylate (tradename: ARONIX M-240, from TOAGOSEI CO., LTD.) was added to the aqueousemulsion containing natural rubber based particles obtained above andwell stirred, thereafter, by elevating the mixture at 50° C. followed byremoval of moisture vaporized in vacuo to substitute the dispersedmedium in 1 hr. Herein, the weight ratio of aqueous emulsion containingnatural rubber based particles to polyethylene glycol diacrylate was160:100.

On the other hand, in 100 parts by weight of acryloyl oligoester wasdissolved 100 parts by weight of the photopolymerization initiator(trade name: VICURE 55, from Akzo Nobel), followed by adding this 10parts by weight into 200 parts by weight of the above dispersed mediumsubstituent to afford ultraviolet curing type pressure-sensitiveadhesive composition 3-1.

When measured the moisture content of pressure-sensitive adhesivecomposition 3-1 obtained, it was 0.5 wt %. The average particle diameterof the natural rubber based particles was 0.2 μm and the dispersibilitywas uniform.

The pressure-sensitive adhesive composition 3-1 was applied in order to6 g/m² on form high-quality paper (trade name: NIP N (70 kg rangeamount) from Oji Paper Co., Ltd.) using a wire bar, followed by beingcured using high-pressure mercury lamp to form the adhesive layer and togive sheet for carrying information 3-1. The applicability also in thecases of whole application and pattern application was well similarly tothe case of low absorbable paper. There was no generation of poor statessuch as poor drying and the like.

After layered together with two surfaces forming the adhesive layer ofsheet for carrying information 3-1 obtained, a sealing machine was setto 160 μm of a gap between rollers to do sealing. After sealing, twoforms adhered with sufficient strength. When detached these two forms,they could be finely detached without detachment between the adhesivelayer and the substrate.

EXAMPLE 3-2 Adhesive Composition 3-2 And Sheet for Carrying Information3-2

In order to be adjusted to 100 parts by weight to 100 parts by weight ofnatural rubber based particles, 91 parts by weight of polyethyleneglycol diacrylate (trade name: ARONIX M-240, from TOAGOSEI CO., LTD.)and 9 parts by weight of acryloyl oligoester were added to the aqueousemulsion containing the same natural rubber based particles as used inadhesive composition 3-1 and well stirred, thereafter, by elevating themixture at 50° C. followed by removal of moisture vaporized in vacuo tosubstitute the dispersed medium in 1 hr.

To this was added 4 parts by weight of the photopolymerization initiator(trade name: VICURE 55, from Akzo Nobel) to afford ultraviolet curingtype pressure-sensitive adhesive composition 3-2.

When measured the moisture content of pressure-sensitive adhesivecomposition 3-2 obtained, it was 0.5 wt %. The average particle diameterof the natural rubber based particles was 0.2 μm and the dispersibilitywas uniform.

The pressure-sensitive adhesive composition 3-2 was applied in order to6 g/m² on form high-quality paper (trade name: NIP N (70 kg rangeamount) from Oji Paper Co., Ltd.) using a wire bar, followed by beingcured using high-pressure mercury lamp to form the adhesive layer and togive sheet for carrying information 3-2. The applicability also in thecases of whole application and pattern application was well similarly tothe case of low absorbable paper. There was no generation of poor statessuch as poor drying and the like.

After layered together with two surfaces forming the adhesive layer ofsheet for carrying information 3-2 obtained, a sealing machine was setto 100 μm of a gap between rollers to do sealing. After sealing, twoforms adhered with sufficient strength. When detached these two forms,they could be finely detached without detachment between the adhesivelayer and the substrate.

EXAMPLE 3-3 Adhesive Composition 3-3 And Sheet for Carrying Information3-3

In order to be adjusted to 100 parts by weight to 100 parts by weight ofnatural rubber based particles, ethylene glycol diglycidyl ether (tradename: Epolite 400E, from KYOEISHA CHEMICAL Co., LTD.) was added to theaqueous emulsion containing the same natural rubber based particles asused in adhesive composition 3-1 and well stirred, thereafter, byelevating the mixture at 50° C. followed by removal of moisturevaporized in vacuo to substitute the dispersed medium in 1 hr. Herein,the weight ratio of aqueous emulsion containing natural rubber basedparticles to polyethylene glycol diacrylate was 160:100.

On the other hand, in 100 parts by weight of acryloyl oligoester wasdissolved 100 parts by weight of the photopolymerization initiator(trade name: VICURE 55, from Akzo Nobel), followed by adding this 10parts by weight into the above dispersed medium substituent to affordultraviolet curing type pressure-sensitive adhesive composition 3-3.

When measured the moisture content of pressure-sensitive adhesivecomposition 3-3 obtained, it was 0.5 wt %. The average particle diameterof the natural rubber based particles was 0.2 μm and the dispersibilitywas uniform.

The pressure-sensitive adhesive composition 3-3 was applied in order to6 g/m² on form high-quality paper (trade name: NIP N (70 kg rangeamount) from Oji Paper Co., Ltd.) using a wire bar, followed by beingcured using high-pressure mercury lamp to form the adhesive layer and togive sheet for carrying information 3-3. The applicability also in thecases of whole application and pattern application was well similarly tothe case of low absorbable paper. There was no generation of poor statessuch as poor drying and the like.

After layered together with two surfaces forming the adhesive layer ofsheet for carrying information 3-3 obtained, a sealing machine was setto 160 82 m of a gap between rollers to do sealing. After sealing, twoforms adhered with sufficient strength. When detached these two forms,they could be finely detached without detachment between the adhesivelayer and the substrate.

EXAMPLE 3-4 Adhesive Composition 3-4 And Sheet for Carrying Information3-4

To 100 parts by weight of natural rubber based particles in adhesivecomposition 3-1, in order to set from Takeda Chemical Industries, Ltd.SBR (trade name: CROSLENE SK-72) as 15 parts by weight, in order to setcommercially available silica of average particle diameter 4 μm as 50parts by weight and in order to set commercially available wheat starchof average particle diameter 15 μm as 150 parts by weight, the similaroperation was performed except adding these fillers to obtain adhesivecomposition 3-4. The operation similar to the case of sheet for carryinginformation 3-1 was performed to obtain sheet for carrying information3-4. The adhesive composition 3-4 and sheet for carrying information 3-4obtained had good performance.

EXAMPLE 3-5 Adhesive Composition 3-5 And Sheet for Carrying Information3-5

In place of acryloyl oligoester used in adhesive composition 3-1, byusing ethylene oxide-modified succinic acid acrylate, β-carboxyethylacrylate, ω-carboxy-polycaprolactone monoacrylate, a copolymer of 50parts by mole of ethyl acrylate and 50 parts by mole of lauryl acrylatehaving average 5.6 mole of carboxyl groups in one mole molecule,2-acryloyloxyethyl phthalate, and the like, adhesive composition 3-5 andsheet for carrying information 3-5 may be obtained. The adhesivecomposition 3-5 and sheet for carrying information 3-5 obtained havegood performance.

Industrial Applicability

An adhesive composition wherein natural rubber based particles areuniformly dispersed in a radiation setting compound is cured byradiation to make a pressure-sensitive adhesive layer on a substrate,thereby: sufficient adhesiveness is obtained; different fillerssufficiently charged; drying time after application is short; bothoverall application and pattern application are readily performed;application can be performed on different substrates; and sufficientadhesive strength between the substrate and the pressure-sensitiveadhesive layer can be realizes. This adhesive composition may bemanufactured by: mixing aqueous emulsion containing the natural rubberbased particles and the radiation setting compound; elevating atemperature of the mixture while stirring; removing vaporized water inthe aqueous emulsion; and replacing the water as the medium wherein thenatural rubber based particles are dispersed by phase transition withthe radiation setting compound.

1. An adhesive composition, comprising a natural rubber based particleuniformly dispersed in a radiation setting compound.
 2. An adhesivecomposition according to claim 1, wherein said radiation settingcompound is at least one compound having two or three radiationpolymerizable functional groups in a molecule.
 3. An adhesivecomposition according to claims 1 or 2, wherein a ratio of saidradiation setting compound to 100 parts by weight of said natural rubberbased particle is 50 parts to 500 parts by weight.
 4. An adhesivecomposition according to claim 1, wherein a moisture content is not morethan 10 wt %.
 5. An adhesive composition according to one of claims 1,wherein said natural rubber based particle is a copolymer of a naturalrubber based rubber and at least one of an acrylic monomer and a styrenebased monomer.
 6. An adhesive composition according to claim 1, whereinan average particle diameter of said natural rubber based particle is0.01 mm to 5 mm.
 7. An adhesive composition according to claim 1,wherein said radiation setting compound is at least one of an acryliccompound and a cyclic ether-containing compound.
 8. An adhesivecomposition according to claim 7, wherein said acrylic compound is afirst acrylic compound of 50 to 1,000 in weight average molecular weighthaving at least one (meth)acryloyl group.
 9. An adhesive compositionaccording to claim 7, wherein said cyclic ether-containing compoundcontains at least one epoxy ring.
 10. An adhesive composition accordingto claim 1, further comprising a second acrylic compound.
 11. Anadhesive composition according to claim 10, wherein said second acryliccompound is at least one of an acrylic monomer and an acrylic oligomerof 2 to 10 in polymerization degree.
 12. An adhesive compositionaccording to claim 1, further comprising a carboxyl group-containingacrylic compound.
 13. An adhesive composition according to claim 12,wherein said carboxyl group-containing acrylic compound is an ester form(I) having a structure where epoxide(meth)acrylate having a hydroxylgroup is bonded with a polycarboxylic acid by ester.
 14. An adhesivecomposition according to claim 12, wherein said carboxylgroup-containing acrylic compound is an ester form (II) having astructure where a hydroxy acid or a hydroxy acid polymer is bonded witha (meth)acrylic acid by ester.
 15. An adhesive composition according toclaim 12, wherein said carboxyl group-containing acrylic compound is a(meth)acrylic polymer (III) having a carboxyl group.
 16. A sheet forcarrying information, comprising a pressure-sensitive adhesive layerconsisting of a radiation setting material of the adhesive compositionaccording to claim 1 formed on a substrate sheet.
 17. A method ofmanufacturing the adhesive composition according to claim 1, comprising:mixing an aqueous emulsion containing said natural rubber based particlewith said radiation setting compound; and elevating a temperature of themixture while stirring, removing vaporized water from the aqueousemulsion and replacing a water by said radiation setting compound as amedium wherein the natural rubber based particle are dispersed.
 18. Amethod of manufacturing the adhesive composition according to claim 17,wherein a ratio of said radiation setting compound to 50 parts by weightof said natural rubber based particle is 25 parts to 250 parts byweight.